Chuck mechanism for a stoper rock drill



. Feb. 4, 1958 J. c. CURTIS 2,821,963

CHUCK MECHANISM FOR A STOPER ROCK DRILL 4 mea oct. 21,1952

l I l. 75g 4% Si# f 3'/ a n #n J A W v'l i Il INVENTYoR l U gm Q `lol-m C.CuRT|s P J BY W l I ATToRNEY United States Patent CHUCK MEcHANisM FOR A sToPER Rock DRILL John C. Curtiis, Newport, N. H., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application october 21, 1952, serial No. 315,999 l 1 ciaim. (ci. 121-32) This invention relates to rock drills and more particularly to an improved chuck mechanism for a hammer rock drill of the stoper type especially designed for use in drilling upright overhead holes.

In a stoper rock drill, and particularly in a stoper drill of the roof bolting type such as is commonly employed in underground coal mines, it is highly desirable to keep the overall length of the drill at a minimum. In such drills, which may be either of the dry or the wet type, considerable difficulty has been encountered, while maintaining minimum overall length, in sealing out foreign matter, such as cuttings, grit and water, from the internal chuck parts, and since such seals have heretofore not been completely effective considerable wear has occurred resulting in considerable air leakage and in decreased drilling eiliciency. Also, some diiculty has been encountered in such rock drills in the maintenance of alignment between the moving chuck parts such as the tappet, chuck bushing and chuck sleeve. The present invention contemplates improvements over known types of stoper rock drills in that the difficulties have outlined are substantially overcome. ln accordance with the present invention the tappet or striking block has been combined with the sliding chuck bushing and is guided for reciprocatory movement in a stationary front bushing xed within the front chuck housing so that not only is the combined tappet and bushing adequately supported and guided but also an effective seal due to the large bearing surfaces is provided which prevents foreign matter, such as cuttings, grit and Water, from flowing into the interior of the chuck mechanism. By combining the tappet with the sliding chuck bushing and by guiding the same within the bore of a stationary wear bushing, the overall length of the drill is maintained at a minimum. The improved chuck mechanism is relatively simple and rugged in design, well adapted for its intended purpose.

It is accordingly the primary object of the present inventionl to provide ah improved chuck mechanism for a stoper rock drill wherein the overall length of the drill is maintained at a minimum and the moving chuck parts are effectively guided and sealed against foreign matter thereby to reduce wear and increase drilling efficiency. Another object is to provide an improved combined tappet and sliding chuck bushing construction. Yet another object is to provide an improved rock drill chuck mechanism wherein the number of the moving parts is reduced, resulting in simplification and increasing durability. A further object is to provide an improved sliding chuck bushing and tappet construction for a hammer rock drill together with improved guiding and sealing means therefor. These and other objects and advantages of the invention will, however, hereinafter more clearly appear in the course of the ensuing description.

In the accompanying drawing there are shown for purposes of illustration one form and a modification which the invention may be assumed in practice.

In this drawing:

Fig. 1 is a view in central longitudinal section taken ice 2A through a hammer rock drill in which an illustrative form of the improved chuck mechanism is embodied.

Fig. 2 is a cross section taken on the planes of line 2-2 of Fig. 1.

Fig. 3 is a perspective view of the guide bushing.

Fig. 4 is a perspective view of the combined tappet and sliding chuck bushing.

Fig. 5 is a fragmentary view, taken on the plane of Fig. 1, illustrating a modified construction.

Fig. 6 is a cross section taken on the planes of line 6-6 of Fig. 5.

The hammer rock drill in which the invention is embodied is generally designated 1 and comprises a conventional uid actuated hammer motor having a cylinder 2 containing a reciprocable hammer piston 3, the latter having a forwardly projecting striking bar 4. The motor cylinder has a usual front buffer ring or head 5 provided with a bore in which a wear bushing 6 is tted for guiding the piston striking bar during reciprocation of the hammer piston, and secured to the cylinder is a front chuck housing 7 which is suitably held in engagement with the front cylinder head, as shown in Fig. l. The hammer piston, as is usual in rock drills of the type disclosed, is intermittently rotated as it reciprocates, and a spirally grooved rie bar 8 is slidingly interlocked within the piston, and rifle bar movement is controlled l automatically by a conventional ratchet and pawl mechanism (not shown). The piston striking bar has straight longitudinal grooves 9 which are slidingly interlocked with straight splines or lugs 10 of a conventional chuck nut 11 secured, as by a key, within a rotatable chuck sleeve l2, the latter being rotatably mounted in axially aligned bores 13 and 14 of the front cylinder head 5 and chuck housing 7 respectively. Thus, as the hammer piston reciprocates within the motor cylinder the chuck sleeve 1l is intermittently rotated.

Now referring to the improved chuck mechanism it will be noted that a combined tappet or striking block and sliding chuck bushing 16 has an elongated forward cylindrical portion 17 formed with a hexagonal socket 18 for receiving the polygonal shank 19 of a conventional collared rock drill steel 20. Formed rearwardly of the cylindrical portion 17 of the combined tappet and chuck busliing 16 is a rearward transverse solid portion 21 formed exteriorly with lateral key projection, splines or lugs 2A which are slidingly interlocked within longitudinal grooves or keyways z3 formed within the forward portion of the rotatable chuck sleeve 12. The rearward portion 2l of the combined tappet and chuck bushing lo is axially perforated at 24 and a conventional cleansing fluid conducting tube 2S extends axially through the rille bar and hammer piston and through the axial perforation 24 luto the rearward portion or the axial bore Z6 of the drill steel 20, and this tube may conduct either fluid under pressure or water through the drill steel for hole cleansing purposes in a well-known manner.

In this improved construction a front wear bushing 27 has a press lit within the forward portion of the bore 14 of the chuck housing 7 and the chuck housing has an inwardly directed, internal, annular flange 28 which provides a rearwardly facing shoulder against which a shoulder 29 on the wear bushing abuts, as shown in Fig. l, and the wear bushing has a reduced forward circular portion 30 which extends axially through and has a close running tit with the bore of the annular llange 28. 'l'hi's wear bushing 27 has a straight unitorm bore 3 1' which has a close sliding til with the forward cylindrical portion I7 of the combined tappet and chuck bushing 16, thus providing a large bearing suri'ace for the cnuck bushing and affording an ell'ective dirt seal between the parts. The rear end of the bore 3l of the wear bushing 27 is desirably chamfered or tapered at 32 and the keys orv lugs'`22of"the`slidng`bushing 16 are formed with inclined forwardlyx facing surfaces 33N-whichI Y'conform with the tapered surface 32 of-.the wear bushing and move into contact with the. surfaceA 32 when the sliding bushing 16"`is` in its foremost' position. Thel vsl'idingbushing 16, when 'in 'its rearmost position,`abuts 'at`341a"shoulder within the chucksleeve rearwardly of"the 'splineways 23 for limiting the inward movementof the bushing.

The'rockdrill'inFig. 1 is for`iillust'r'ative purposes 'shown 'in a horizontal position 'butfin actual use as -a s'toper extends vertically to en-able "drilling fot vertical overhead holes. .'AstheA hammer"pi'ston 3 reciprocates within the motor cylinder` t-he'piston striking bar' 4 imparts a rapid series of impact blws toA therear end.' surface 3S ofthe combined tappet vand.chuck bushingl and the solid Vtappet portion 21 has -a'forwardlyac'ing internal `impact surface'36 which transmits the impact'hl'ows4 of the Vpiston striking bar tothe rear end of the'shk 19 of the drill steel thereby to percussively actuate t-he'lat'ter to effect drilling -of a hole. cares it is intermittently rotated by the ratchetand pawl controlled rifle bar 8 and the intermittent pis-ton rotation :is transmitted through the chuck nut 11 and chucksleeve 12 and through the splines 23 and keys Z2 of :the sliding .bushing to the drill steel intermittently to rotatethe' latter as it ispercussively actuated. During reciprocation of the hammer piston the combined tappet and chuck bush- '.ing.16 slides-freely axially relative to the. chuckfsleeve while the tappet. andbushing .is at. Iall 'times maintained slidingly interlocked with .the chuck sleevethrough the keys and splineways.

`Inthe-modiiied construction shownA in Figs. and"6 it .will be noted that the parts of the chuck mechanism-are essentially the same as those ofthe embodiment aboveldescribed .and are designated by similar reference numerals. In this instance,y however, the chuck sleeve-12lhas elon- ,gatedsplinewaysvZS which are slidingly interlocked with lelongated keys or lugs 22'v formed on a combinedftappe't and sliding chuck bushingl. The elongated cylindrical portion 17 of-the sliding bushing is slid'ingly-mounted withinl and has-a close running `tit with theY bore 31 of ya iront wear bushing l27'tirmly secured-within the chuck housing. VThe combined tappet or striking blo'ckandslidingchuck bushing 16.is,-fin this instance, composed of ftwo. separable; parts comprising a` forward; chuck. bushing part 16' .and a. rearward tappet part '21' .and -thebushing is. formed at its. rearward; portion "with an` axial 'bore 38 within Whichxa forward cylindricalvprojeotion.S9-fon the tappetthas-a tighttpress Yliti. lLThebushing-'part :16' has .extending axially therethrough a hexagonalbored which slidingly receives :theashank 319 of thendrill '-s-teel. The tappet `part-21 .has La'. lcylindrical -body which mayhaveya sliding t within a bore'z40zwithin the`chucksleevez12i so .that the combined; tappetiand-` slidingJbushing` may-.be lade- Aquately-g guidedati -itstopposilteends `although guidingoffthe bushing solelyby Vthe frontfwearbushing is desira'blersince vexact alignment, Vwith suchaiconstruction, of ,therchuck sleeve and chuck bushing 'fisiunnecessary. Theifreplace- `able tappet part 21.hasarearwardly.facingv'impact receiving surface lf-35.and the forward-.cylindrical projection .39 provides aforwardly: facing impact; surfacer;and,v a's in the embodimenbabove describednthepiston striking .bar 4i isv adapted` toideliverraseriesaof; rapidzfimpa-ot blows togthe t-appetsurface 35'fandtthe tappetrpart transmits `theseblows through .the .impacttsurfacefxto fthe rear end .of thesteel shank-19. 'Asgfintheiot'her embodiment" the combined tappet andtchuckbushing hasrfreeslidingifmovement relative -to thefehuckleeve'while-itt is-'rnaintaimed.v in lSliding f interlocking engagement fwith the lchuck isleeve. By making the. tappetsparte-zl'eseparable. vfrom,.thegbushing :part A16'4v ittis a possible atoabroachL-.t-he bore .-.18 completely As the 'hammer pistonreciproreadily replaced `when wit'becomes worn or broken.

4 throu-gh the bushing, and the separate tappet part may be Otherwise this embodiment is similar to that above described.

As a result of this invention an improved chuck mechanism is provided for a stoper type rock drill wherein the overall length of the drill is kept at a minimum and the internal chuck structure is `adequately sealed against entry of dirtor other -foreign matter. `By combining the tappet with the sliding chuckbushing not only is the length of the drill maintained at a minimum but also the drillfj'structurejis simplified and durability lis. in.- crea`sed. "By'slidingl'yinounting' tne forward cylindrical portion of the combined tappet and sliding chuck bushing withintheiunilform straight lbore of'f-a stationary wear bushing, not only is an effective seal between the parts provided but a1so'an"improved bearing mounting for the bushing is afforded. These and other advantages of the invention will be clearly apparent to those skilled in theart.

While there-are 'in' ithis application' specitically described one form"andfa mcdilic'ation which 'the invention 'may assume in practice, it will'be"understoodfthat this form Of-the-sa'rne isishown'forpurposesof illustration and that the 'invention may beifurther modified and embodied invarious-ot-her fo'rmswvithout Adeparting* from its spirit or thef'scope ofthe appended claim.

AWhat I-`claimas neWand desire'tosecure' by Letters Patent is:

vlnr Combination, Ia motor cylinder containing a reciprocatory hammer "pistonfa front chu'ck housing secured to said-'cylinderarid-having arforwardg bore,` ay cylindrical Vfront 4vwear'bushing,secured within the" forward portion Vof said `-hou'sing=bore,'a rotatable' chuck sleeve having a cylindrical'forward'portion 'rotatably mounted within said housingbore rearwardly of `saidwear bushing, a cornbined rotative and 'reciprocatory'A tappetA andl chuck bushing-having' a cylindricalfexterior surface at'itsforward portionendadapted to receive the 'impact blowsdelivcred Vby said piston,l saidcombined' tappet and vchuck bushing havinga socketifor'slidingly receiving theshank of a reciprocatory "dtilljsteel 'and' relative'- to which said steelshank has freerecipro'catory slidirigmov'ement during the'percussive vactuzt'tion thereof, said combined tappet and chuck bushingi'ha'ving its forward port-ion slidingly Aguided within'sa'idfrontwear'bushingwith the latter providing the -solle bearing "support for said combined tappet-and chuck bushing, said combined tappetand chuck bushing' extending freely Irearwardly `from said wearbushing into thefbore of said chuck sleeve, and *means at Ythe rearward'portion'oflvsaidcombined tappet `-and chuck bushing providing a-'relatively loosely viitted 'sliding interlocking vconnection between sa'id 'combined tappet and chucky bushing and the forward portion of 'said chucky sleevewherebyisaid combined tappet and chuck bushing Vlmayf-slidin'gly"reciprocatel freely! relative to said "chucki sleeve 'ias it rotatesI -inunison with thelatter, said `vfront Swear 'bushing 'having ai bore of-:substan'ti'al length vandsadfcomhine'd tappetandfchuck bushing having its 'forward-'portionLelongatedland lslidingly 2guided in and -havi-ng 4a .close sliding-t with Usaid wear-bushing-bore wherebysaid combined tappet' and chuck bushing is at al1-times Vadequately :guidedland supported entirely .by said LAwear '..bu'shing `while :such sliding vtit provides an effectivedirt'seal between the parts.

.RcferencesfCited in thele of this. patent "UNITED STATES LPATENTS 12,458,289 lMorrison c n Jan. 4, l1949 72,608,180 Cur'tis Aug. 26, 1952 42,508,181 "Curtis et al. Aug. l26, 19,5 2 2,608,413 "Peck 4Allgf26, i952 

